1. Field of the Invention
The present invention relates to multilayer electronic components, and more particularly, to a method for manufacturing a miniaturized thin-film multilayer electronic component, such as a thin-film multilayer capacitor, having a relatively high capacitance and further relates to such a thin-film multilayer electronic component.
2. Description of the Related Art
A monolithic ceramic capacitor, which is typical of multilayer electronic components, is generally manufactured through the following steps:
(1) An electrode paste is printed on ceramic green sheets having a predetermined size.
(2) Then, a predetermined number of the ceramic green sheets are layered on one another, and ceramic green sheets not printed with the electrode paste are further layered on the upper and lower surfaces of the layered ceramic sheets, followed by contact-bonding under predetermined conditions to prepare a laminate.
(3) The laminate is cut into individual elements and the individual elements are subjected to heat treatment to remove a binder and fired.
(4) An electrode paste is applied to each fired element and burned to form external electrodes.
Thus, the resulting ceramic capacitor conventionally has a chip structure in which a plurality of internal electrodes are each disposed between two ceramic layers and the external electrode are each connected to predetermined internal electrodes.
In such a process for manufacturing a monolithic ceramic capacitor, however, the thickness of each dielectric layer, namely, the ceramic layer, depends on the particle size of the ceramic powder material. Thus, it is impossible to form a thin dielectric layer having a thickness smaller than the particle size of the ceramic powder material.
Also, in order to prevent short circuiting and breaking of electrodes resulting from a defect of the dielectric layers, and to ensure reliability, the thickness of the dielectric layers needs to be 3 μm or more. This makes it difficult to reduce the size of the monolithic ceramic capacitor and increase the capacitance.
As a solution of the above-described problem, a method for manufacturing a thin-film multilayer capacitor in which dielectric layers and internal electrodes are deposited by sputtering, which is one of the methods for forming a thin film, has been proposed in Japanese Unexamined Patent Application Publication No. 56-144523. In this method, Al2O3, SiO2, TiO2, or BaTiO3 dielectric thin films and thin-film internal electrodes are deposited on a substrate by sputtering, and external electrodes functioning as lead terminals of the internal electrodes are formed by applying and burning an electrode paste. Thus, the method facilitates the manufacture of a thin monolithic ceramic capacitor.
In addition, another method for manufacturing a multilayer capacitor has been disclosed in Japanese Unexamined Patent Application Publication No. 2-121313. In this method, at least three thin-film internal electrodes and at least two dielectric thin films, such as of BaTiO3, are formed on an insulative substrate to prepare a thin-film laminate. The ends of the internal electrodes extend to the outside of the laminate, and external electrodes are formed on both ends of the substrate, including the ends of the internal electrodes, by a dry technique.
However, since, in those techniques for manufacturing a multilayer capacitor using thin films, external electrodes are disposed on both end surfaces of the laminate and substrate, it is necessary to cut the thin-film laminate on the substrate into chip-shaped pieces before the formation of the external electrodes.
In the case of manufacturing an ultra-miniature chip capacitor, unfortunately, it is difficult to handle chips, into which a wafer is cut, to form the external electrodes, and this negatively affects production efficiency.
The above-described problems hold true for other thin-film multilayer electronic components without being limited to the thin-film multilayer capacitors.